In routine practice of Radiotherapy (RT), the subject is positioned relative to the stationary center of the rotating arc carrying the RT source. Positioning implies both height and lateral adjustment of the subject table. This positioning is required to optimize the dose in the lesion beyond variation that can be obtained by applying RI rays from different angles.
Integration of MR and Linear Accelerators (LINAC) opens new horizons in Radiotherapy by improved lesion targeting, especially for moving organs. In a practical implementation proposal, the LINAC rotates around the subject to hit the gross target volume (GTV) and clinical target volume (M) from multiple angles while minimizing the radiation exposure for surrounding tissues.
The combination of magnetic resonance apparatuses and LINAC radiotherapy sources is known. Typically a LINAC source is placed on a rotating gantry about the magnet and designing the magnet such that the LINAC rotates in a zero-field region of the magnet. Another particular feature of the concept is the use of a split gradient coil which prevents attenuation of the LINAC beam.
In Champagne et. al. “A Novel Radiolucent Phased Array Design Suitable for MR Guided Radiation Therapy,” Proc. Intl. Soc. Mag, Resort. Med 19 (2011) an X-ray transparent phased array coil for magnetic resonance imaging is described. The coil was constructed so that a combination of thicknesses of copper and the solid FR4 substrate such that it will be transparent during x-ray imaging and radiation therapy.